Refrigerating process



June 2, 1931.

s. c. cARNEY E1' AL REFRIGERATING PROCESS Fiied Feb'. 15, 1926 Patented June 2, 1931 UNITED STATE-s PA'rs-N'lv OFFICE -SAIMUEL C. CARNEY, OF TULSA, ROBERT E. BAKER,A OF DRUMRIGHT, AND FRANK C. CUTTING, F TULSA, OKLAHOMA, ASSIGNORS TO SHELL PETROLEUM CORPORATION,

g A GORPORATION OIEI VIRGINIA REFRIGERATING PROCESS Application nled February 15, 1926. Serial No. 88,489.

This invention relates to improvements in. `refrigerating processes.

An object of the invention is to provide a multi-stage refrigeration process, using in l each stage a compound hydro-carbon refrigerant characterized so as to give a low Aratio of compression at the evaporating and condensin tem eratures of each respective stage of tie re rigeration cycle.

The drawing illustrates in diagrammatic form a plurality of refrigerating units with their connections. y

The apparatus shown' in the drawing is intended to be Aillustrative only and it will, of course, be understood that the practice of the process is not limited to any particular form of apparatus.

Byoproviding a `refrigeration process com- 2. prising a plurality of stages and bydetermining refrigerating agents having di'erent vjevaporation points under predetermined pressures, and utilizing the refrigerating action of 'the refrigerant in the adjacent stage for condensing the evaporated liquid of the next stage, comparatively low pressures are -required and lower temperatures may be attained Without loss of eiiiciency.

For example, a series of hydro-carbon refrigerating agents, such, for instance, as methane, ethaue and butane, may be utilized in a four-stage refrigerating process, so that the fluid to be cooled is subjected to Vthe refrigerating action due to the expan- 'sion of methane,.which, after expansion, is condensed by evaporating in the next adjacent stage the refrigerating agent comprising ethane, and then Vcondensing ethane by utilizing `the refrigerating agent butane, which in turn may be condensed under the cooling action of water at normal temperature.

s While we have given an example of suitable refrigerating agents'for the multi-stage process, mixtures made from selecting and compounding a hydro-carbon refrigerant differing for each stage andwith aV vapor pressure adapted to the pressure and. temperature conditions of the particular stave, may be selected.- Thus,lthe pressure un er Vwhich the condensation ofv each refrigerant takes ratio. v

In the drawi'n an apparatus for a'. fourstage system is ustrated. The fluid to be cooled is circulated around the tubes of an exchanger 1, the liquid being introduced through an inlet plpe 2 and discharged through a'discharge pipe 3. Within the tubes of the exchanger 1, the mostvolatile hydro-carbon compound of the series used i's evaporated, and. the vapor of the .refrigerant is withdrawn through the conduit 4 by a lcompressor 5, from which it is delivered to the exchanger 6 throughV a conduit v- In the tubes of the exchanger 6, a rerigerant of a lower degree of volatility is evapA orated, which results `in the condensation of the vapor of the next higher degree of volatility introduced into the exchanger 6. The condensed refrigerant is returned through a return passage 8 to the tubes of the exchanger 1, the passage 8'being con-v trolled by an expansion valve 9. The vapor of the refrigerant expanded in the exchanger 6 in turn is conducted throu h a passage 10 to acompressor 11, from w ich it 1s forced under pressure through'the passage l2 to the exchanger 13 in the tubes of Which'a refrigerant of a lower degree of volatility is evaporated, thereby condensing the vapor, which is returned through the passage 14 equipped with an expansion valve 15 to theA exchanger 6 for re-evaporation. i

The vapor ofthe refrigerant in the exchanger 13 is exhausted through the conduit-16, compressed in acompressor 17, and introduced through=a conduit 18 into the exchanger 19, which is `cooled by a ow of cooling water through the tubes thereof introduced through an inlet pipe 20 and discharged through a discharge pipe 21, the condensed vapor returning to the exchanger 13 through a conduit 22 equipped with an place may be held at a relatively 10W.

'expansion valve 23. It is thus apparent that the vapor in each stage is compressed at low temperatures and at economical compression ratios.

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Itis contemplated that the whole apparatus will be heat insulated.

Any suitable means may be employed for supplying to each stage a suicient amount of the refrigerant to make up for loss in evaporation and leakage, and instead of using acompressor for exhausting the vapor of the evaporating refrigerant,` an absorption method may be emplo ed. c

.- It is not intended to limit the process by the usev of any particular apparatus, but what is claimed and desired to be secured by Letters Patent is:

1 'A refrigeration system which consists in expanding a series of refrigerants or different boiling points, subjectln the vapor of the expanded refrigerant o the lower )boiling point to the cooling action of the refrigerant of higher boiling point, the last of '20 said series of refrigerants condensing at substantially atmospheric pressure, and subjectingv a fluid to be cooled to the cooling action of the low boiling point refrigerant.

`2. A system of refrigeration which comprises the progressive expansion and condensation by compression and cooling of a series of refrigerants having varying boiling oints from a boiling point at which the rerigerant condenses at substantially atmos-V pheric pressure to a oint suiiiciently low to substantially cool a uid, and subjecting theiuid to be cooled to the cooling action of the low boiling point refrigerant.

3. A methodl of refrigeration comprising the alternate evaporation and condensation of a raded series of refrigerating agents,

the high boiling point refrigerant condensing approximately at atmospheric pressure and atmosphericy temperature, and subject- 40. ing the material to be cooled to the cooling action of the lowest boiling point refrigerant only. 4 SAMUELv C. CARNEY. 4 t ROBERT E. BAKER. 5 FRANK C. CUTTING. 

